The present invention relates to a replaceable ear wax guard to be arranged in an opening of an acoustic outlet passage or in a vent in a housing designed for placement in the ear canal of an in-the-ear hearing aid.
In in-the-ear hearing aids where the hearing aid housing is placed within the user""s ear canal with the acoustic outlet port facing the inner ear and connected to the telephone unit of the hearing aid, it is a well-known problem that the acoustic outlet passage is exposed to contamination with cerumen or ear wax which may lead to clogging of the acoustic outlet passage with consequently reduced sound reproduction. At worst, there may be a risk for the ear wax to enter the hearing apparatus housing and result in damage to the electrical components of the hearing aid.
In order to avoid this problem, it is known from U.S. Pat. No. 4,972,488 to arrange a replaceable ear wax barrier, which can at the same time provide a dampening of the acoustic response, in the acoustic outlet passage in the apparatus housing. In this known design, the ear wax barrier is formed as a screw plug the arrangement of which presupposes a thread being provided in the acoustic outlet passage, and the ear wax barrier is in the end facing outward at the insertion by screwing, designed with incisions for providing a slot for a screw driver. The barrier effect for retaining of ear wax is obtained by providing inward projections in a through-going cavity in the screw plug.
As a consequence of the very small dimensions where the acoustic outlet passage has typically a diameter of about 1 mm, the screw plug form entails that insertion and removal of the ear wax guard is a rather difficult operation, especially for weak-sighted hearing aid users, and the inward projections forming a kind of maze in the through-going cavity do not provide full security against migration of ear wax. Furthermore, the screw plug design cannot be used in in-the-ear hearing aids of the conventional type where the acoustic outlet passage is formed by a short hose or tube member connecting the telephone unit with an acoustic output port in the wall of the hearing aid housing.
Furthermore, the international patent application WO 84/04016 discloses an ear wax guard in the form of an outwardly closed plug with a disc-shaped head which at the placement of the plug covers the acoustic outlet port of the aid housing. In the plug under the disc-shaped head, there are provided radial acoustic passageways in connection with a longitudinal acoustic passageway opening in the plug end introduced in the aid housing. To secure a sufficient acoustic passage, the plug is designed such that the disc-shaped head is kept at a distance from the outside of the aid housing which entails a risk, albeit reduced, of migration of ear wax under the plug and in the narrow radial acoustic passageways. As a consequence of the smooth disc-shaped head, the insertion and removal of the plug is also in this case a difficult operation.
In a hearing aid known from U.S. Pat. No. 4,553,627, an essentially mushroom-shaped ear wax guard with a crossing acoustic passage is mounted with snap engagement in metal ring inserted in the acoustic outlet port of the hearing aid housing.
On the background of this prior art, it is the object of the invention to provide a replaceable ear wax guard of the stated type with a simple and low-cost design suited for all kinds of in-the-ear hearing aids and which can be mounted in and removed from the aid housing in a simple way.
For this purpose, the ear wax guard according to the invention is characterized in that it comprises an essentially tubular element adapted to the mouth diameter of the acoustic outlet passage or the vent and having a through-going cavity which in one end is partially closed by an ear wax retaining guard whereas the element in the opposite end is connected to a surrounding abutment collar for sealing abutment against the hearing aid housing around the acoustic outlet port or vent, said element being made by an elastical yielding material and said through-going cavity at its mouth in the abutment collar being adapted for introduction of a means to be used when the ear wax guard is inserted in and removed from the acoustic outlet port or the vent.
As a consequence of the simple design as a short tubular element with a surrounding abutment collar in the end facing inward at the insertion, the ear wax guard according to the invention is inexpensive to manufacture in a large number by moulding of the elastical yielding material, which can typically be silicone rubber or a thermoplastic elastomer. A further contribution to this is the positioning of the ear wax retaining barrier in one end of the tubular element which when introduced is led into the acoustic outlet canal. The merely partial opening of this end of the tubular element can be obtained by designing the guard as a kind of screen and thus can assure a good sound transmission.
Advantageous features and embodiments of the ear wax guard are indicated in the dependent claims 2-5. In a particularly advantageous embodiment, in particular for use in connection with CIC hearing aids, the abutment collar is provided with a convex outside and a concave or faintly conical underside so that its periphery edge forms a sealing lip against the aid housing. Thus, the user comfort is improved as the ear wax guard essentially follows the outer contour of the aid housing.
As a consequence of the sealing abutment of the abutment collar of the ear wax barrier against the hearing aid housing, the abutment collar, which can preferably be provided with a relatively thin and soft edge, fitting snugly to the surrounding outside of the housing with a very even transition, it is avoided that when inserting or removing the hearing aid, the abutment collar causes any inconvenience or damage to the ear canal.
As the removal of the wax barrier in a conventional way by seizing the edge of the abutment collar as known from said US publications is thus made more difficult, the invention further concerns a means to be used for insertion of an ear wax guard, characterized in that it comprises an essentially rod-shaped applicator which in one end is provided with a smooth pin fitting the mouth of the through-going cavity of the ear wax guard for use at insertion of the ear wax guard whereas in the opposite end it is provided with a catch member for use at removal of the ear wax guard and engaging the wall inner side of the through-going cavity when pressed into its mouth.
By this applicator design, the insertion of the ear wax guard in the acoustic outlet port and the removal herefrom in connection with the replacement of the ear wax guard can be made in a simple way and with a high degree of security even by weak-sighted users, the different design of the two ends of the applicator for insertion and removal, respectively, contributing to the easy operation.
Advantageous embodiments of the means are indicated in the dependent claims 7-13. Thus, according to a preferred embodiment, the essentially cylindrical and wedge-shaped portion of the applicator is separated by an intermediate piece with a cross section larger than said portion, and the means comprises further a enlargement lens with a bore provided for attachment on said cylindrical or said wedge-shaped applicator portion in abutment against said intermediate piece.
Thus, a further improvement of the operating security is obtained, especially for weak-sighted hearing aid users.
As from consideration of the visibility of the through-going cavity of the ear wax guard and the risk of pressing ear wax accumulated in the ear wax guard out through the ear wax retaining barrier at insertion of the applicator in the ear wax guard in connection with the removal hereof, the catch member may not cover a too large area, the use of the applicator, especially in ITE hearing aids where the acoustic outlet canal is designed as a hose or tube member guided from the output transducer of the aid all the way through to the acoustic outlet port in the wall of the housing, will entail a certain risk that such a hose or tube member and perhaps the ear wax guard itself at the pressing-in of the catch member is pressed into the hearing aid housing.
To encounter this risk, the invention concerns in addition a particularly designed in-the-ear hearing aid for arrangement of the ear wax guard and with a housing provided for positioning in the ear canal and having an essentially shell-shaped wall, in which an acoustic outlet port and perhaps a vent are provided in an end part meant for placement in the ear canal, where the acoustic outlet port is in connection with one end of hose or tube member serving as acoustic outlet port, the other end of which is connected to an outlet port from an outlet transducer situated in the housing.
To obtain an improved security against the hose or tube member serving as acoustic outlet canal at the mounting or replacement of the ear wax guard being detached from its connection with the acoustic outlet port in the end part of the housing wall and pressed into the housing, the hearing aid according to the invention is characterized in that the hose or tube member with a view to positioning an ear wax guard as stated above is connected to an annular abutment collar in abutment with the outside of said wall end part.
Appropriate embodiments for such a hearing aid are stated in the dependent claims 15-22.
Since the housing for in-the-ear hearing aids of the stated kind is usually designed with an individually adapted form according to the actual user""s ear canal, the invention further relates to a method for manufacture of a hearing aid of the stated type which permits a production of the abutment collar for mounting of the ear wax guard in a standard design independent of the individual user adaptation of the form of the housing.
According to the invention, this method is characterized in that an abutment collar is used with over-dimensioning in relation to said end part of the housing wall, and that the abutment collar by preparation of its periphery edge is formed to a flush transition with the outside of said end part.